SEOUL, March 2 (Yonhap) -- Two F-5F fighter jets crashed into a mountain near Gangneung, about 237 kilometers east of Seoul, during a training mission on Tuesday, officials and witnesses said.

The safety of all three pilots, let alone the cause of the crash, has yet to be confirmed, they said, adding a search is under way.

The two jets crashed into Mount Hwangbyeong, about 20 kilometers west of Gangneung, Gangwon Province, at 12:20 p.m., a defense ministry official said, asking to remain anonymous.

"We are currently searching for the missing pilots near the area," the official said, adding two HH-60 rescue helicopters have been dispatched.

Some mountain climbers reported to local fire stations that they have found wreckage of military jets near the top of Mount Hwangbyeong, according to officials.

The Air Force has yet to confirm the crash of the two jets, saying that the jets disappeared from radar just five minutes after a take-off from a base in Gangneung on the eastern coast.

"The two jets disappeared from the radar near Gangneung. We are currently searching for the missing pilots near the area," an Air Force spokesman said, withholding information about the missing. "There is high possibility that the aircrafts crashed due to bad visibility from the foggy weather. We will further investigate the causes."

The crash, if confirmed, would mark the seventh time for the aging jet to crash in the country since 2000.

The F-5 fighter jets, first produced during the 1970s in the United States, have been deployed in South Korea since the 1980s. Weapons experts say the life expectancy of fighter jets is no longer than three decades.

Two South Korean pilots died in 2004 after two F-5E jets crashed in the Yellow Sea in 2004 and another four servicemen died the following year while F-5F and F-4E jets crashed into the same sea during separate drills.

In the most recent case, two F-5E fighter jets crashed in Pocheon, just 46 kilometers northeast from Seoul, in November 2008, according to data by Seoul's defense ministry.